1. Field of the Invention
This invention relates to a coated shaped article of a polycarbonate type resin. More particularly, this invention relates to a coated shaped article of a polycarbonate type resin excelling in abrasion resistance, formed by coating a shaped substrate of a polycarbonate type resin with an undercoating paint highly adhesive to the polycarbonate type resin, allowing the applied undercoat to cure, subsequently coating the undercoated shaped substrate with an overcoating paint containing a silicon type resin and allowing the applied overcoat to cure.
2. Description of the Prior Arts
Generally, polycarbonate type resins excel in impact resistance and transparency and, therefore, are widely used as transparent plastic materials. They nevertheless have a disadvantage that, because of deficiency in resistance to abrasion and solvents, they tend to sustain scratches on the surface and yield to the action of an organic solvent. To remedy this fault, various methods for coating such polycarbonate type resins have been proposed. None of these methods, however, have provided any satisfactory remedy.
For example, combinations of trialkoxysilanes such as methyl trialkoxysilanes and phenyl trialkoxysilanes with tetraalkoxysilanes such as ethyl silicate and butyl silicate and mixtures of such combinations with other resin paints have been known as coating compositions. None of them have proved completely satisfactory in such properties as abrasion resistance, adhesiveness, hot water resistance, thermal resistance and weather resistance. Japanese Patent Publications No. 15,743/1978 and No. 35,589/1978 disclose coating compositions which comprise epoxy group-containing alkoxysilanes and curing catalysts such as BF.sub.3, BF.sub.3 etherate and other Lewis acids, complexes of such acids, HCl, HBr, HI, HNO.sub.3, HClO.sub.3, H.sub.3 PO.sub.4 and other Bronsted acids. These coating compositions have a short pot life and exhibit deficient adhesiveness to polycarbonate type substrates. U.S. Pat. No. 3,986,997 discloses a coating composition comprising coloidal silica and hydrolyzate of methyltri methoxy silane as a main component. Although the cured coating film has sufficient hardness, it has poor flexibility, and it is very difficult to obtain good adhesiveness to the polycarbonate type resin substrate. Japanese Laid-Open Patent Publication No. 111,336/1978 discloses coating compositions comprising one or more of mixtures selected from compounds containing epoxy group and silanol group and/or siloxane group and fine divided silica having a particle diameter of from 1 to 100 milimicrons and an aluminum chelate compound, but the cured coated film has poor hardness and the hardness decreases by boiling, dipping into water and the like, and further, it exhibits poor adhesiveness to a bisphenol type polycarbonate substrate.
It is, therefore, an object of this invention to provide a coated shaped article of a polycarbonate type resin, the coat of which exhibits high resistance to abrasion, hot water, heat and weather conditions and offers improved adhesiveness to the substrate.
It is an another object of this invention to provide a process for producing the coated shaped article of the polycarbonate type resin.